1 /* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */
2 /*
3 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
4 * Optimized by Bruce D. Evans.
5 */
6 /*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 *
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
13 * is preserved.
14 * ====================================================
15 */
16
17 use super::{k_cosf, k_sinf, rem_pio2f};
18
19 /* Small multiples of pi/2 rounded to double precision. */
20 const PI_2: f32 = 0.5 * 3.1415926535897931160E+00;
21 const S1PIO2: f32 = 1.0 * PI_2; /* 0x3FF921FB, 0x54442D18 */
22 const S2PIO2: f32 = 2.0 * PI_2; /* 0x400921FB, 0x54442D18 */
23 const S3PIO2: f32 = 3.0 * PI_2; /* 0x4012D97C, 0x7F3321D2 */
24 const S4PIO2: f32 = 4.0 * PI_2; /* 0x401921FB, 0x54442D18 */
25
26 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
sincosf(x: f32) -> (f32, f32)27 pub fn sincosf(x: f32) -> (f32, f32) {
28 let s: f32;
29 let c: f32;
30 let mut ix: u32;
31 let sign: bool;
32
33 ix = x.to_bits();
34 sign = (ix >> 31) != 0;
35 ix &= 0x7fffffff;
36
37 /* |x| ~<= pi/4 */
38 if ix <= 0x3f490fda {
39 /* |x| < 2**-12 */
40 if ix < 0x39800000 {
41 /* raise inexact if x!=0 and underflow if subnormal */
42
43 let x1p120 = f32::from_bits(0x7b800000); // 0x1p120 == 2^120
44 if ix < 0x00100000 {
45 force_eval!(x / x1p120);
46 } else {
47 force_eval!(x + x1p120);
48 }
49 return (x, 1.0);
50 }
51 return (k_sinf(x as f64), k_cosf(x as f64));
52 }
53
54 /* |x| ~<= 5*pi/4 */
55 if ix <= 0x407b53d1 {
56 if ix <= 0x4016cbe3 {
57 /* |x| ~<= 3pi/4 */
58 if sign {
59 s = -k_cosf((x + S1PIO2) as f64);
60 c = k_sinf((x + S1PIO2) as f64);
61 } else {
62 s = k_cosf((S1PIO2 - x) as f64);
63 c = k_sinf((S1PIO2 - x) as f64);
64 }
65 }
66 /* -sin(x+c) is not correct if x+c could be 0: -0 vs +0 */
67 else {
68 if sign {
69 s = -k_sinf((x + S2PIO2) as f64);
70 c = -k_cosf((x + S2PIO2) as f64);
71 } else {
72 s = -k_sinf((x - S2PIO2) as f64);
73 c = -k_cosf((x - S2PIO2) as f64);
74 }
75 }
76
77 return (s, c);
78 }
79
80 /* |x| ~<= 9*pi/4 */
81 if ix <= 0x40e231d5 {
82 if ix <= 0x40afeddf {
83 /* |x| ~<= 7*pi/4 */
84 if sign {
85 s = k_cosf((x + S3PIO2) as f64);
86 c = -k_sinf((x + S3PIO2) as f64);
87 } else {
88 s = -k_cosf((x - S3PIO2) as f64);
89 c = k_sinf((x - S3PIO2) as f64);
90 }
91 } else {
92 if sign {
93 s = k_sinf((x + S4PIO2) as f64);
94 c = k_cosf((x + S4PIO2) as f64);
95 } else {
96 s = k_sinf((x - S4PIO2) as f64);
97 c = k_cosf((x - S4PIO2) as f64);
98 }
99 }
100
101 return (s, c);
102 }
103
104 /* sin(Inf or NaN) is NaN */
105 if ix >= 0x7f800000 {
106 let rv = x - x;
107 return (rv, rv);
108 }
109
110 /* general argument reduction needed */
111 let (n, y) = rem_pio2f(x);
112 s = k_sinf(y);
113 c = k_cosf(y);
114 match n & 3 {
115 0 => (s, c),
116 1 => (c, -s),
117 2 => (-s, -c),
118 3 => (-c, s),
119 #[cfg(debug_assertions)]
120 _ => unreachable!(),
121 #[cfg(not(debug_assertions))]
122 _ => (0.0, 1.0),
123 }
124 }
125
126 // PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
127 #[cfg(not(target_arch = "powerpc64"))]
128 #[cfg(test)]
129 mod tests {
130 use super::sincosf;
131 use crate::_eqf;
132
133 #[test]
with_pi()134 fn with_pi() {
135 let (s, c) = sincosf(core::f32::consts::PI);
136 _eqf(s.abs(), 0.0).unwrap();
137 _eqf(c, -1.0).unwrap();
138 }
139
140 #[test]
rotational_symmetry()141 fn rotational_symmetry() {
142 use core::f32::consts::PI;
143 const N: usize = 24;
144 for n in 0..N {
145 let theta = 2. * PI * (n as f32) / (N as f32);
146 let (s, c) = sincosf(theta);
147 let (s_plus, c_plus) = sincosf(theta + 2. * PI);
148 let (s_minus, c_minus) = sincosf(theta - 2. * PI);
149
150 const TOLERANCE: f32 = 1e-6;
151 assert!(
152 (s - s_plus).abs() < TOLERANCE,
153 "|{} - {}| = {} >= {}",
154 s,
155 s_plus,
156 (s - s_plus).abs(),
157 TOLERANCE
158 );
159 assert!(
160 (s - s_minus).abs() < TOLERANCE,
161 "|{} - {}| = {} >= {}",
162 s,
163 s_minus,
164 (s - s_minus).abs(),
165 TOLERANCE
166 );
167 assert!(
168 (c - c_plus).abs() < TOLERANCE,
169 "|{} - {}| = {} >= {}",
170 c,
171 c_plus,
172 (c - c_plus).abs(),
173 TOLERANCE
174 );
175 assert!(
176 (c - c_minus).abs() < TOLERANCE,
177 "|{} - {}| = {} >= {}",
178 c,
179 c_minus,
180 (c - c_minus).abs(),
181 TOLERANCE
182 );
183 }
184 }
185 }
186